Plural sources beverage dispensing apparatus

ABSTRACT

A beveraging dispensing system for mixing and dispensing soft drink syrup concentrates and mixing soda supplied under pressure to a hand-held control and dispensing head having a plurality of mechanically actuated control valves wherein displacement of the valves is assisted by the pressure and flow of the mixing soda.

United States Patent [191 Hanson [451 Feb.4, 1975 PLURAL SOURCES BEVERAGE DISPENSING APPARATUS [75] Inventor: Sigurd A. Hanson, Los Angeles,

Calif.

[73] Assignee: Bar Mates Fluidic Systems, Inc., Los

Angeles, Calif.

[22] Filed: Oct. 9, 1973 [2|] Appl. No.: 404,307

Sheardown 137/62518 X Carothers et a1. 222/1445 X Primary ExaminerR0bert B. Reeves Assistant ExaminerFrancis J. Bartuska Attorney, Agent, or FirmHarris, Kern, Wallen & Tinsley [57] ABSTRACT A beveraging dispensing system for mixing and dis pensing soft drink syrup concentrates and mixing soda supplied under pressure to a hand-held control and dispensing head having a plurality of mechanically actuated control valves wherein displacement of the valves is assisted by the pressure and flow of the mixing soda.

4 Claims, 4 Drawing Figures pka'ss'mlzsu SODA 12 fissur /zap swap saunas preess'wrzsp SyAv/P Saunas 1 PLURAL SOURCES BEVERAGE DISPENSING APPARATUS My invention relates to beverage dispensing systems and more particularly to carbonated soft drink dispensing systems where the soft drink is a mixture of a flavored syrup concentrate and carbonated water both supplied under pressure to a hand-held dispensing head.

Typically, such systems remotely locate the source of the beverage ingredients and offer a choice of beven ages. Provisions may be made to select, direct. and control the flow of the selected beverage by manipulation of a valve control and dispensing means which may be hand-held.

Since the introduction of multiple beverage dispensers, electromechanical valve mechanisms have been provided as a means for controlling the flow of the beverage ingredients. The mechanisms used have included solenoid armatures acting in direct axial alignment with a movable valve element and impact type solenoid valves utilizing intermediate linkages between the armature of the solenoid and movable portions of the valves. In theory, these designs have shared the common objectives of providing a small, lightweight, reliable hand-held valve control means having a plurality of valves for offering a selectivity of beverages. In practice, however, these objectives have not been fully or satisfactorily achieved primarily because of electrical design problems. For example, because of size constraints, designers have used electromechanical components of small size and capable of generating only marginally effective forces for valve actuation. A marginally sufficient force tends to result in slow valve actuation speeds which tend to produce beverage dilution since the high viscosity of the concentrated flavoring syrup retards its flow through an only partially open valve while the carbonated mixing soda is a freely flowing fluid through a similarly only partially open valve. Further since mixing soda is most often at a higher level of pressurization than the syrups in order to maintain its carbonation, its rate of flow is typically much higher than for any corresponding amount of syrup valve opening which aggravates the problem of maintaining exactness of proportion between simultaneously dispensed beverage ingredients. The proportion control, of course, contributes to the palatability and acceptance of the beverage.

Because of the only marginally effective forces generated by small-sized electromechanical elements when operated at conservatively rated current levels, designers have tended toward reducing the safety margins of allowable current. This has lead to perhaps the most frequent cause of electromechanical valve control breakdown or inoperativeness, namely, control switch contact erosion and solenoid coil burn out. Beyond such problems, it is of course recognized that electromechanical valve mechanisms for controling the flow of liquids as in a beverage dispensing system are fraught with electrical shock hazards for the operators thereof.

Accordingly. in view of the foregoing problems it is an object of the present invention to provide a soft drink dispensing system utilizing a hand-holdable valve control means free of electrically controlled elements and their attendant problems.

Another object of the present invention is to provide such a soft drink dispensing system of the foregoing character wherein the actuation of a single control valve releases exact amounts of flavored syrup concentrate and mixing soda by utilizing the pressure of the mixing soda to assist the operation of the control valve.

A further object of the present invention is to provide a soft drink dispensing system of the foregoing character including a valve control means of simple and rugged construction yet rapid operation.

Still another object of the present invention is to provide a soft drink dispensing system of the foregoing character wherein the valve control means includes a plurality of mechanically actuated valves in a housing. each valve associated with a different source of syrup and soda under pressure and each valve including a spindle carrying a plurality of spools for directing the simultaneous flow of syrup and soda to a dispensing head.

A still further object of the present invention is to provide a soft drink dispensing system of the foregoing character wherein the soda coacts with a lower spool on each spindle to assist in the rapid closing of the valves upon release from an open condition.

The foregoing as well as other objects and features of the present invention may be more clearly understood by reference to the following detailed description when considered with the drawing, which, by the way of example only, illustrates one configuration of a soft drink dispensing system embodying the features of my present invention.

In the drawing:

FIG. I is an over-all pictorial and diagrammatic view showing the soft drink dispensing system of my present invention;

FIG. 2 is a sectioned view taken along line 2-2 of FIG. 1;

FIG. 3A is a partially sectioned internal view taken along the line 33 in FIG. 1 showing a valve of my valve control means in its closed position; and

FIG. 3B is a partially sectioned view similar to FIG. 3A showing a valve of my valve control means in its open position.

Generally speaking, the illustrated form of my soft drink dispensing system includes a plurality of beverage syrup sources such as l0, l2 and 14, a source of carbonated water or soda 16, and a fully mechanical valve control means 18. The concentrated syrups in the sources l0, l2 and 14 are maintained at a low pressure relative to the soda in the soda source 16 and all the sources are located remote from the valve control means for separate connection thereto by flexible conduit 20 housed in a hose structure 22. The valve control means 18 includes a plurality of similar fully mechanical valve 24 in a lightweight hand-holdable housing 26. The housing 26 includes a plurality of fluid inlets 28 each connected to a different conduit 20 and a fluid outlet means 30 connected to a mixing and dispensing head 32. Each valve, such as 240 in FIGS. 3A and 3B, is associated with a different one of the syrup sources and the soda source, and with a different push button 34 protruding from a cover and retaining plate 36 located on top of the housing. The valve 24 and porting in the housing 26 from the conduits 20 to the mixing and dispensing head 32 are such that a manual depression of the push button 34 associated with a valve such as 24a in FIGS. 3A and 38 produces a substantially instantaneous downward movement of the valve to a fully open position to permit the simultaneous and full flow of a syrup such as orange concentrate and soda through the valve control means 18 to the head 32 for dispensing as orange soda into a glass or cup. Similarly, a manual depression of the push button 34 associated with another of the valves 24 produces a substantially instantaneous movement of that valve to a fully open position to permit the simultaneous and full flow of a different syrup such as cola concentrate, and soda through the valve control means for dispensing a carbonated cola beverage at the head 32. In each instance. a release of the valve by removal of a downward force on the associated button 34 results in an extremely rapid and automatic return of the valve to its normally closed position. Such closing of the valves is assisted by coaction of soda from the soda source I6 with a lower spool 38 carried on a spindle 40 for each valve. As will be described in greater detail hereinafter, the pressure assist provided by the soda acting on the lower spool 38 of each valve allows for a highly compact design of the valve control means free of electromechanical devices, mechanical linkages, and/or heavy springs to effect the desired valve movement with the valve control.

As previously indicated, each of the valves 24 is of a similar construction and operates in a similar manner. Accordingly, only the details of the valve 240 will be described hereinafter with reference to FIGS. 3A and 38, it being understood that a similar construction and operation is associated with each of the other valves in the valve control means 18.

In more specific detail, and referring to the drawing, the valve 240 includes a cylindrical valve cavity 42 in the housing 26 receiving a movable valve body 44 comprising the spindle 40 carrying the spool 38 as well as spools 46 and 48. As depicted in FIGS. 3A and 33, depression of the valve body 44 from the closed position in FIG. 3A to the open position in FIG. 3B permits soda and syrup to simultaneously flow through porting in the housing 26 into the cavity 42 and past the spools to porting leading to the fluid outlet and dispensing head 32. A release of the valve body 44 results in a rapid and automatic return of the spindle 40 to the closed position of FIG. 3A to block the flow of syrup and soda.

As illustrated. the valve cavity 42 extends downwardly through an outer top surface 50 of the valve housing 26. While the cavity 42 may be of a generally uniform diameter it includes a bottommost portion having a smaller diameter which forms a spring housing or well 52. In addition four vertically spaced annular grooves 54, 56, 58 and 60 are formed in the side wall of the cavity. The location and spacing between adjacent grooves divides the cavity 42 into four distinct zones. A first zone 64 is formed below the bottom-most groove 54 and includes the aforementioned spring housing or well 52 and a cavity side wall opening designated as a first inlet port 66 formed by an intersecting and horizontally extending passageway 68 for conducting pressurized soda to the valve cavity from an inlet port 28. A second zone 70 is formed above the annular groove 54 and below the groove 56 and includes a side wall opening or first outlet port 72 formed by an intersecting and horizontally extending passageway 74 for conducting pressurized soda away from the valve cavity to the oultet 30. A third zone 76 is formed above the groove 56 and below the groove 58 and includes a side wall opening or second outlet port 78 formed by an intersecting and horizontally extending passageway 80 for conducting flavored syrup away from the valve cavity to the outlet 30. A fourth and uppermost zone 82 is formed above the annuler groove 58 and below the groove 60 and includes a side wall opening or second inlet port 84 formed by an intersecting and horizontally extending passageway 86 for conducting flavored syrup to the valve cavity from an associated inlet port 28. Each of the aforementioned annular grooves carries an O-ring 62a-d for sealing and thereby controlling the flow of either syrup and/or soda through the valve 24a relative to the position ofthe movable valve body 44 in the cavity 42.

In this regard, in the movable valve body 44 the spools 38, 46 and 48 carried by the spindle 40 are located at lower, intermediate, and upper positions along the spindle 40. Further, the spools are dimensioned such that the spool 38 slidably engages and seals against the O-ring 62a in the groove 54, the spool 46 against the O-rings in the grooves 56 and 58, and the spool 48 against the O-ring in the groove 60. In addition, the valve spindle 40 includes a lower portion 88 below the valve spool 38 carrying a coil spring 90. An upper coil of the spring 90 has a natural diameter less than the diameter of the lower spindle portion 88, thereby providing a gripping force for retaining the spring in position on the spindle. The length of the spring 90 is such that it normally extends downwardly from the lower portion 88 into the spring well 52 to engage a bottom thereof (see FIG. 3A). The weight and strength of the spring 90 are such that the spring is only strong enough when compressed in the well 52 to start upward movement of the spindle from the open position of'the valve shown in FIG. 38 toward the closed position shown in FIG. 3A and in the absence of soda at the inlet 64 to urge the spool 38 into nonsealing contact with the lower O-ring 62a. In brief, the spring 90 is a small, light weight spring. The well 52, of course, is sufficiently large to freely receive the spindle end and spring combination. Only the bottom of the well serves as a bottom limit for the free or bottom end of the coil spring. It is not intended that the bottom end of the spindle extension 88 make contact with the bottom of the well 52 as a means for limiting the downward displacement of the valve body 44. Such limitation of downward movement as well as upward movement is provided by the cap 34 and retainer or cover plate 36.

In that regard, the valve retaining plate 36 is secured on the top of the valve housing 26 and includes a plurality of circular holes each having a diameter slightly larger than the outer diameter of an associated push buttom 34. The holes are formed -in a spaced-apart relationship corresponding to the location of the valves 24 as shown in FIG. 1. A concentric and circular recess 92 is formed in the bottom surface of the valve retaining plate 36 relative to each push button clearance hole. The recess 92, in cooperation with the top surface of the valve body serves to restrict the axial displace ment of the push button 34 and, in turn, the displacement of the valve body 44.

In particular, the push button 34 is essentially a cap for fitting over the end of the upper spool 48 of the valve body 44. As clearly shown in FIGS. 3A and 3B the push button 34 is of a hat" shaped cross section having a lower rim 94 of a larger diameter than the upper cylindrical portion protruding upwardly above the top surface 96 of the valve retaining plate 36. The push button 34, in cooperation with the valve retaining plate 36 and the top surface of the housing, provides a means for limiting the axial translation of the valve body 44. As shown in FIG. 3A, an upper annular surface 98 of the rim 96 and an annularly shaped surface I00 of the retaining plate 36 are in contact. With such contact. the valve body 44 is restricted from further axial displacement in an upwardly direction thereby defining a closed position of the valve. The downward displacement of the valve body 44 is similarly limited by engagement of the rim 88 with the top surface of the valve housing as shown in FIG. 38. Here, a lower annular surface 102 of the rim makes contact with the housing surface.

When considering the valve 240 in its closed position as shown in FIG. 3A, several conditions relating to the position of the valve body 44 within the valve cavity 42 are to be noted. The O-ring 62a carried in the lower groove 54 is in sealing contact with the lower spool 38 and pressurized soda fills only the inlet passageway 68 and the valve zone 64 immediately below the spool 38. The next uppermost zone 70, and its associated soda outlet passageway 74 are empty of pressurized soda. The O-ring 62b carried in groove 56 which defines the upper limit of zone 70 is in sealing contact with the intermediate spool 46. At this time the syrup outlet passageway 80 and communicating cavity zone 76 are similarly free of concentrated flavoring syrup due to the sealing of the O-ring 62c carried in the groove 58 against the spool 46. Pressurized syrup fills the passageway 86 and zone 82 located immediately above the intermediate spool 46 and below the upper spool 48. It will be noted that the O-ring 62d carried in the uppermost groove 60 is in sealing contact with the uppermost spool 48 thus preventing leakage of the syrup from the valve cavity. Since pressurized syrup generates equal forces against the top sloping surface of the intermediate spool 46 and the bottom sloping surface of spool 48 the pressurization of the syrup does not contribute toward displacement of the valve body 44.

In order to achieve the full open valve condition as shown in FIG. 38 wherein the valve body 44 is fully displaced downwardly, it is only necessary to initially overcome the opposing force generated by the pressure of the soda bearing against the lower sloping surface of the valve spool 38. In the fully open position the O-ring 62a is no longer in sealing contact with the lower valve spool and soda is free to flow from the inlet passageway 68 through the zone 64 and upwardly into zone 70 and then through the outlet port 70 and associated passageway 74. It will also be noted, that when the valve body is displaced in the full open position, sealing contact between the upper portion of the intermediate spool 46 and the O-ring 62c is no longer maintained. Pressurized syrup is then free to enter the upper zone 82 through inlet passageway 86 and pass downwardly into zone 76 and then into the outlet passageway 80. It is to be noted that in the full open position the intermediate spool 46 remains in sealed contact with the O-ring 62b and thereby prevents an intermingling of the syrup and soda within the valve cavity.

Both outlet passages 74 and 80 conducting soda and syrup respectively away from the valve cavity terminate at an end of the housing 26 in a hole pattern formed in the housing as shown in FIG. 2. The center hole is the terminal discharge opening of the pressurized soda passageway while each of the outlying and smaller diameter holes are terminal passageway openings for conducting pressurized syrup. The dispensing head 32 is in sealed contact with the end of the valve housing and includes the identical pattern of openings at its inlet surface as shown in FIG. 2. The dispensing head exit openings may be continued in the same pattern as shown in FIG. 2 or may be arranged and directed so as to cause a mixing of the pressurized soda and pressurized flavoring syrup upon exiting from the dispensing head.

Turning now to the mechanical actuation of any given valve within my valve control means 18; it has been shown that a simple downward displacement of a single push button 34 is the only requirement to change a given valve from a fully closed position to fully open. In my experience I have found that the pressure of the mixing soda and diameter of the valve spool 38 may be established so as to require a maximum downwardly directed force upon the push button 34 of less than approximately 3 pounds. Additionally, the valve control as I have provided requires only small displacements of the valve body 44 for transition between its fully closed and fully open positions. A small displacement of under one-eighth of an inch accompanied by a relatively high working pressure of mixing soda of approximately 100 psi and coupled with an elasticity inherent to the flexible inlet conduit 20, provides an unique feel" when a valve body 44 is displaced to either its open or closed position. Upon opening and just as an upper edge portion 104 of the lower spool 38 clears contact with its O-ring 620, the inrush of mixing soda filling the subcavity zone and its associated exit passageway 74 causes a partial equalization of pressures between top surface 106 of the valve spool 38 and its bottom surface 108 causing a sudden reduction in the amount of pres sure required to continue the displacement of the valve body 44 toward its fully open position. The operator of my valve control then experiences this sudden reduction in the amount of digitally applied force as a momentary pulse. Thus, the valve l have provided insures transition between a fully closed position and fully opened position as a snap-type" of action which insures uniform proportion control between the flavored syrup concentrate and mixing soda. In any other than an instantaneously opening valve for controlling the flow of two fluids of dissimilar viscosity, the flow of the fluid having heavier viscosity necessarily lags the flow of that fluid with lesser viscosity. As applied to soft drink beverages an overage of mixing soda, the fluid of less viscosity, directly affects the palatability of the beverage.

In addition to the snap-opening characteristic of the valves of my valve control means, I have provided a similar characteristic of the valve upon moving to the fully closed position. In this instance only a slight relaxation of the push button pressure displacing the valve body 44 in its fully open position is required. A momentary pulse, similar in nature to that as just previously described as accompanying the displacement of the valve body 44 from fully closed to fully opened position, accompanies the displacement of the valve body from its fully open to fully closed position. Upon a slight relaxation of digitally applied pressure to the push button 34 the coil spring responds by slightly displacing the valve body 44 upwardly away from the limit stop provided as part of the push button flange. At a point of upward displacement approximately between 50 percent open and 50 percent closed positions, the lower valve spool 38 commences to restrict flow between the sloping surface 108 and the surface of the O- ring 62a. This restriction of flow has the effect of increasing the pressure differential in the mixing soda as measured between the inlet and outlet passageways intersecting the adjacent valve cavity zones 64 and 70.

This increase in differential pressure has the effect of accelerating the displacement of the valve body 44 toward its fully closed position due to the higher pressure of the inlet mixing soda bearing against the lower surface of the spool 38. The valve body 44, accelerated by the pressure of the mixing soda, arrives at its point of uppermost travel while accelerating. The rapid termination of acceleration is afforded by contact of the push button annular surface 98 making contact with the corresponding surface 100 of the valve retaining plate 36. Thus, the instantaneous termination of upward displacement by the valve body 44 is experienced as a momentary pulse by the operator of the valve control. This rapid "shut-of of the flowing concentrated syrup and mixing soda has the desirable effect ofterminating flow ofthe two ingredients having dissimilar viscosities in a manner which insures a balance of proportion between amounts of beverage ingredients entering the outlet passageways 74 and 80.

From the foregoing detailed description, it is to be understood that the soft drink dispensing system of my present invention provides for the convenient selection and dispensing of soft drinks comprising a flavored concentrated syrup and a mixing soda. My hand-held valve control provides for simple, direct acting, and pressure assisted valve operation requiring only a slight amount of thumb or finger movement and force for initializing valve displacement toward its fully opened position, and having been reached, requires only that the externally applied force be momentarily removed to thereby enable the pressure of the mixing soda to take over and displace the valve body to its fully closed position,

Additionally. the precise valve operation afforded by the mixing soda fluid pressure assist enables close proportionate beverage ingredient control and eliminates the previously known problems commonly associated with electromechanical valve control means.

While a particular embodiment of a soft drink dispensing system is described in some detail herein, it is appreciated that changes and modifications may be made in the illustrated form without departing from the spirit of the invention. Accordingly, it is intended that my present invention be limited in scope only by the terms of the following claims,

I claim:

I. A soft drink dispensing system comprising:

a plurality of sources of syrup each maintained at a relatively low pressure;

a source of soda maintained at a relatively high pressure;

a hand-holdable, fully mechanical valve control means having a plurality of fluid inlets and a fluid dispensing head at a fluid outlet thereof; and

conduit means connecting said plurality of syrup sources and said soda source to different inlets of said valve control means; and

said valve control means including a housing,

a plurality of normally closed valves in said housing one for each different syrup source and each including a valve cavity extending from an outer surface of said housing,

a valve spindle in said cavity with an upper end portion exposed beyond said outer surface,

upper, intermediate and lower spools on said valve spindle,

a first inlet port into a side of said cavity immediately below said lower spool,

a second inlet port into a side of said cavity immediately above a top of said intermediate spool and below said upper spool,

a first outlet port from a side of said cavity above said first inlet port and below said intermediate spool,

a second outlet port from a side of said cavity below said second inlet port,

a first seal on an inner wall of said cavity between said first inlet and outlet ports slidably engaging an outer surface of said lower spool to block fluid flow between said first inlet and outlet ports when said valve is in its normally closed position and releasing from said lower spool as said spindle is moved axially into said cavity to define an open position for said valve,

a second seal on an inner wall of said cavity between said first and second outlet ports slidably engaging an outer surface of said intermediate spool to block fluid flow between said second inlet and outlet ports and said first outlet port,

a third seal on an inner wall of said cavity between said second inlet and outlet ports slidably engaging an outer surface of said interme diate spool to block fluid flow between said second inlet and outlet ports when said valve is in said closed position and releasing from said intermediate spool as said valve is moved to said open position,

a fourth seal on an inner wall of said cavity between said second inlet and a top of said cavity slidably engaging an outer surface of said upper spool to block fluid flow from said top of said cavity, and

spring means for urging said valve spindle away from a bottom of said cavity to said closed valve position, said spindle being finger depressible in said cavity to said open valve position, and

conduit means in said housing connecting said first inlet port to said fluid inlet connected to said soda source, said second inlet port to a fluid inlet connected to a syrup source and said first and second outlet ports to said .fluid dispensing head, whereby soda at said relatively high pressure acts on the lower spool of each valve to produce an upward force rapidly moving the valve from said open to closed positions upon a release of its associated valve spindle and an initial upward movement thereof in response to its associated spring means.

2. The system of claim I wherein said spring means comprises a spring dimensioned for location in said cavity and being of a size and weight just sufficient to develop a force for initially moving said spindle away from a bottom of said cavity upon a release of said valve spindle in said open position.

3. The system of claim 2 wherein said spring means includes a coil spring having coils in slidable engage- 9 l ment around a lower end portion of said valve spindle said lower spool along said valve spindle is less than the and at least one upper coil nonslidably engaged thereon distance across said first inlet port measured axially for retaining said coil spring on said valve spindle. along said side of said cavity.

4. The system of claim I wherein the axial length of 

1. A soft drink dispensing system comprising: a plurality of sources of syrup each maintained at a relatively low pressure; a source of soda maintained at a relatively high pressure; a hand-holdable, fully mechanical valve control means having a plurality of fluid inlets and a fluid dispensing head at a fluid outlet thereof; and conduit means connecting said plurality of syrup sources and said soda source to different inlets of said valve control means; and said valve control means including a housing, a plurality of normally closed valves in said housing one for each different syrup source and each including a valve cavity extending from an outer surface of said housing, a valve spindle in said cavity with an upper end portion exposed beyond said outer surface, upper, intermediate and lower spools on said valve spindle, a first inlet port into a side of said cavity immediately below said lower spool, a second inlet port into a side of said cavity immediately above a top of said intermediate spool and below said upper spool, a first outlet port from a side of said cavity above said first inlet port and below said intermediate spool, a second outlet port from a side of said cavity below said second inlet port, a first seal on an inner wall of said cavity between said first inlet and outlet ports slidably engaging an outer surface of said lower spool to block fluid flow between said first inlet and outlet ports when said valve is in its normally closed position and releasing from said lower spool as said spindle is moved axially into said cavity to define an open position for said valve, a second seal on an inner wall of said cavity between said first and second outlet ports slidably engaging an outer surface of said intermediate spool to block fluid flow between said second inlet and outlet ports and said first outlet port, a third seal on an inner wall of said cavity between said second inlet and outlet ports slidably engaging an outer surface of said intermediate spool to block fluid flow between said second inlet and outlet ports when said valve is in said closed position and releasing from said intermediate spool as said valve is moved to said open position, a fourth seal on an inner wall of said cavity between said second inlet and a top of said cavity slidably engaging an outer surface of said upper spool to block fluid flow from said top of said cavity, and spring means for urging said valve spindle away from a bottom of said cavity to said closed valve position, said spindle being finger depressible in said cavity to said open valve position, and conduit means in said housing connecting said first inlet port to said fluid inlet connected to said soda source, said second inlet port to a fluid inlet connected to a syrup source and said first and second outlet ports to said fluid dispensing head, whereby soda at said relatively high pressure acts on the lower spool of each valve to produce an upward force rapidly moving the valve from said open to closed positions upon a release of its associated valve spindle and an initial upward movement thereof in response to its associated spring means.
 2. The system of claim 1 wherein said spring means compRises a spring dimensioned for location in said cavity and being of a size and weight just sufficient to develop a force for initially moving said spindle away from a bottom of said cavity upon a release of said valve spindle in said open position.
 3. The system of claim 2 wherein said spring means includes a coil spring having coils in slidable engagement around a lower end portion of said valve spindle and at least one upper coil nonslidably engaged thereon for retaining said coil spring on said valve spindle.
 4. The system of claim 1 wherein the axial length of said lower spool along said valve spindle is less than the distance across said first inlet port measured axially along said side of said cavity. 